EBV is detected in B cells. Photomicrographs of PBMCs stained by Immuno-FISH from patients 17 (A) and 8 (B) show EBV in the nucleus of B cells (arrows). EBV DNA was identified with the biotinylated FISH probe and streptavidin-conjugated Alexa 488, B cells using a combination of Alexa 647–conjugated anti-CD19 and anti-CD20 antibodies (Biolegend), T cells with Alexa 594–conjugated anti-CD3 antibody (Invitrogen), and monocytes with V450-conjugated anti-CD14 antibody (BD Biosciences). Arrows indicate EBV-positive cells.